Stethoscope



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STETHOSGOPE Filed Aug. 3, 1935 2 Sheets-Sheet 1 Hans von Ba assen A Home s.'

April 26, 1938. H. voN BASSEN STETHOS COPE Filed Aug. 3, 1935 2 Sheets-Sheet 2 wfg@ A Harm/ys' Patented Apr. 26, 1938 UNITED STATES STETHOSCOPE Hans von Bassen, Novaves, near Potsdam, Germany Application August 3, 1935, Serial No. 34,617

In Germany 3 Claims.

My invention relates to stethoscopes and it is an object of my invention to provide an improved instrument of this kind.

To this end, I arrange, in combination with a casing and a stethoscope diaphragm on the casing, a microphone which is arranged in the casing and spaced from its inner wall and equipped with a membrane, and I further provide means for securing the microphone exclusively to the stethoscope diaphragm.

Acoustic stethoscopes are still used for the auscultation of the heart and the lungs, in which the sound is simply transmitted. Doctors use the old wooden stethoscopes, or membrane stethoscopes with rubber tubes extending to both ears, which are better than wooden stethoscopes. However, the sound intensity is frequently not sufllcient in the old stethoscopes, particularly, if very low noises in the body are auscultated.

It has been proposed to provide electric stethoscopes with amplifying valves for radio reception, but such apparatus are only suitable for llecture rooms or the like, and not for the daily use of the practitioner.

My novel microphone stethoscope is without the for practical use.

The stethoscope diaphragm is placed on the part to `be auscultated directlyl or indirectly, by means of an extension. This stethoscope diaphragm supports the microphone which is exclusively secured to, and held by, the diaphragm. Preferably, the stethoscope diaphragm is connected to at least one membrane of the microphone by means of a pin.

Preferably, I provide a microphone with two membranes spaced by adjustable stays, screws or the like. The membranes support two electrodes, and' a body of carbon powder is held between the two electrodes by a ring of felt or ton wool forming a cavity for its reception.

j n the accompanying drawings, several stethos opes embodying my invention are illustrated by way of example.

In the drawings Fig. 1 is an axial section of a stethoscope in which a microphone and a telephone receiver are housed in separate compartments of a casing,

Fig. 2 is an axial section of a stethoscope in A which the telephone receiver is arranged outside the casing,

Fig. 3 is an axial section of a casing with a microphone and a telephone receiver housed therein, substantially as shown in Fig. 1, but modiiied in some details,

Fig. 4 is a plan view of Fig. 3,

Fig. 5 is an axial section of a stethoscope casing with means for direct sound transmission, without using the microphone,

w Fig. 6 is an axial section of a modincation of drawbacks of the old stethoscopes and is adapted`v August 4, 1934 the' construction shown in Figs. 1 and 3, with a part oi' the casing containing the telephone receiver broken away.

Referring now to the drawings, and iirst to Fig. 1, a stethoscope casing I vis subdivided into two compartments 9 and I0 by a transverse partition II. .A microphone 8 is housed in the lower compartment 9 of the stethoscopecasing I and connected to a stethoscope diaphragm 6 at the lower end of the casing by a pinV l. The diaphragm 6 may be of any suitable material, such as textile fabric under strong tension.

A telephone receiver I3 is arranged in the upper compartment I0 of the casing I, and a rubber tube 2 conducts the sound to the ears of the stethoscopist. Current is supplied by a battery 4, a cable 3, and plug'contacts I2 on the casing I.

Referring nowto Fig. 2, the casing I of this stethoscope has only a single compartment for the reception of the microphone 8 which is connected to the diaphragm 6 by the pin 1, as described withy reference to Fig. l. The telephone receiver I3 is arranged outside the casing I, and equipped with rubber tubes 5, each with an end mem-ber 6 for inserting it into the auditory passage.

The casing I is equipped with a hollow handle I5 in which the elements I6 of an electric battery are inserted. The electrodes at the ends of the battery are connected to the microphone by a contact IT, and to the conductor 3 by a contact I8.

The walls of the casing I are comparatively thick and the mass of the casing plus' the battery is very considerable as against' the mass of the microphone 8. By these means, the casing is rendered practically free from oscillations.

Referring now to Figs. 3 and 4, the microphone 8 and the telephone receiver` I3 are arranged in the respective chambers 9 and I0 of the casing I, as described with reference to Fig. 1 but the lower end of the casing is closed by a transverse partition or end wall I4. The stethoscope diaphragm 6 is secured to a flange 20 projecting from the end wall I 4 by an annular holder 2|. The pin I which supports the microphone 8, enters the lower compartment 9 through a central hole in the end wall I4.

The microphone 8 will now be described in detail. It has two membranes 26 and 2l which may be of mica. The lower membrane 26 has a central 50 hole for the reception of the reduced upper end of pin 1. The two diaphragms are connected 'bi The lower end of pin 'I projects beyond the lower surface of the stethoscope diaphragm 6, and a head 30 is placed on the projecting end. 'I'he head supports an extension 3| which is placed on the body, or member, to be auscultated. This extension of the stethoscope` diaphragm 6 may be tubular, as shown.

The telephone receiver I3 in the upper compartment l0 is connected to a sleeve 3" which is inserted in the top wall of the casing I, and the tube 2 is inserted in the sleeve 3".

The plug contacts I2 for connecting the battery 4 have already been described. A contacting arm I9 is mounted to rotate about the axis of the casing I and cooperates with a set of fixed contacts 22 designated by the numerals 0-5, Fig. 4, for cutting in various resistances by which the intensity of the sound reproduction is increased or reduced.

The connections for the electric current are shown in Fig. 3. The current passes from batte'ry I6 through wire 3 over contacting arm I9, the fixed contacts 22 into the casing I, then through a wire 42 into the microphone 8, and from the microphone through a wire 43 to the telephone, and from the telephone through wire 3 to battery I6.

The stethoscope illustrated in Figs. 3, 4, and 6 may be modified in various ways. Thus, as shown in Fig. 6 the lower end of casing I may be closed by an end wall 32 below the diaphragm E which has a central opening in which the extension 3| is free to move. Preferably, a tubular guard 33 is placed on the end wall 32 to surround the extension 3| in spaced relation. The tubular guard 33 should be somewhat shorter than the extension 3|, so that, when the stethoscope is placed on the patients body, the extension 3| first bears against the body. The tubular guard engages the body only after the extension 3| has been forced back, so that the stethoscopeis held against the body very steadily. A guiding membrane 34 is preferably inserted between the extension 3| and the tubular guard 33. The guide membrane 34 is of elastic material, for instance, soft rubber, and extends substantially in parallel relation to the stethoscope diaphragm 6. It is held in the tubular guard 33 at its perimeter and connected to the extension 3| at its centre, at some distance from the stethoscope diaphragm 6. The object of the guiding membrane 34 is to prevent lateral oscillations of the extension 3| which involve corresponding oscillations of the microphone, while it does practically not interfere with the movement of the extension 3| in its longitudinal direction, i. e., atI right angles to the stethoscope diaphragm 6 and the microphone membranes 26 and 21.

Referring now to Fig. 5, this casing which may be a cap or plug for connection with a principal casing is provided with the stethoscope diaphragm 6, the pin 1, and the microphone 8, as described but in addition it has two passages 29 at opposite sides of the pin "I between the stethoscope diaphragm 6 and the microphone 8,

- for transmitting the sounds directly and without invention, the noises in the body of the patient are reproduced extraordinarily clearly and intensely. It has been found that such stethoscopes are especially suitable for making sound records of the noises. Heretofore, extra amplifying means were required between the stethoscope and the electric receiver which normally also amplifles the sound. With the stethoscope according to my invention, the extra amplifying means are dispensed with, and the stethoscope can be directly connected to a normal electric sound receiver, thereby facilitating very much the making of sound records. The same battery may supply the electric sound receiver and the stethoscope.

Sound records of the kind described may be used for recording phenomena of diseasein hospitals, for lectures, investigations, etc.

I claim:

1. In a stethoscope, a casing having an opening therein, a stethoscope diaphragm secured to said casing to close said opening, a microphone arranged in the casing and spaced from its inner wall, said microphone comprising a membrane in the microphone, a telephone receiver connected to the microphone, a source of current connected to the receiver, means for securing said microphone with its membrane to said stethoscope diaphragm so that said microphone and its membrane are freely movable with said diaphragm, and a member projecting from the outer surface of said diaphragm and secured to saiddiaphragm for engaging the body of the patient.

2. In a stethoscope, a casing having an opening therein, a stethoscope diaphragm secured to said casing to close said opening, a microphone arranged in the casing and spaced from its inner wall, said microphone comprising a membrane, a telephone receiver connected to the microphone, a source of current connected to the receiver, means for securing said microphone with its membrane to said stethoscope diaphragm, a member projecting from the outer surface of said diaphragm and secured to said diaphragm for engaging the body of the patient, and a tubular guard secured to said casing and somewhat shorter than said projecting member and surrounding it in spaced relation for engaging the body only after said projecting member has been forced back.

3. In a stethoscope, a casing having an opening therein, a stethoscope diaphragm secured to said casing to close said opening, a microphone arranged in the casing and spaced from its inner wall, said microphone comprising a membrane, a telephone receiver connected to the microphone, a source of current connected to the receiver, means for securing said microphone with its membrane to said stethoscope diaphragm, a member projecting from the outer surface of said diaphragm and secured to said diaphragm for engaging the body of the patient, a tubular guard secured to said casing and somewhat shorter than said projecting member and surrounding it in spaced relation for engaging the body only after said projecting member has been forced back, and a membrane of elastic material inserted between the projecting member and the guard and extending substantially parallel to said stethoscope diaphragm at some distance therefrom.

HANS von BAssEN. 

